Mechanism-based design of 2,3-benzodiazepine inhibitors for AMPA receptors

AMPA receptor neurotransmission and therapeutic applications: A comprehensive review of their multifaceted modulation

The neuropharmacological community has shown a strong interest in AMPA receptors as critical components of excitatory synaptic transmission during the last fifteen years. AMPA receptors, members of the ionotropic glutamate receptor family, allow rapid excitatory neurotransmission in the brain. AMPA receptors, which are permeable to sodium and potassium ions, manage the bulk of the brain's rapid synaptic communications. This study thoroughly examines the recent developments in AMPA receptor regulation, focusing on a shift from single chemical illustrations to a more extensive investigation of underlying processes. The complex interplay of these modulators in modifying the function and structure of AMPA receptors is the main focus, providing insight into their influence on the speed of excitatory neurotransmission. This research emphasizes the potential of AMPA receptor modulation as a therapy for various neurological disorders such as epilepsy and Alzheimer's disease. Analyzing these regulators' sophisticated molecular details enhances our comprehension of neuropharmacology, representing a significant advancement in using AMPA receptors for treating intricate neurological conditions.

Electrophysiological Assessment of Newly Synthesized 2,3-Benzodiazepine Derivatives for Inhibiting the AMPA Receptor Channel

Three major subtypes of ionotropic receptors regulate glutamatergic synaptic transmission, one of which is α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPARs). They are tetrameric, cation-permeable ionotropic glutamate receptors found across the brain. Abnormalities in AMPA receptor trafficking and synaptic assembly are linked to cognitive decline and neurological diseases such as Alzheimer's, Parkinson's, and Huntington's. The present study will investigate the effects of four novel 2,3-benzodiazepine derivatives on AMPA receptor subunits by comparing their effects on synaptic responses, desensitization, and deactivation rate in human embryonic kidney cells (HEK293T) recombinant AMPAR subunits using whole-cell patch-clamp electrophysiology. All four 2,3-BDZ compounds showed inhibitory activity against all the homomeric and heteromeric subunits tested. While the desensitization and deactivation rates in 2,3-BDZ-1 and 2,3-BDZ-2 decreased and increased, respectively, in the other two compounds (i.e., 2,3-BDZ-3 and 2,3-BDZ-4), there was no change in the desensitization or deactivation rates. These results contribute to a better understanding of AMPARs by identifying potential 2,3-BDZ drugs that demonstrate inhibitory effects on the AMPAR subunits.

In silicoinvestigation of Alliin as potential activator for AMPA receptor

Natural products from plants, such as flavonoids, arouse immense interest in medicine because of the therapeutic and many other bioactive properties. The molecular docking is a very useful method to screen the molecules based on their free binding energies and give important structural suggestions about how molecules might activate or inhibit the target receptor by comparing reference molecules. Alliin and Allicin differ from many other flavonoids because of containing no benzene rings and having nitrogen and sulfur atoms in their structure. In this study Alliin and Allicin affinity on AMPA, NMDA and GABA-A receptors were evaluated in the central nervous system by using the molecular docking method. Both Alliin and Allicin indicated no inhibitory effects. However Alliin showed significant selectivity to human AMPA receptor (3RN8) as an excitatory. The binding energy of glutamate to 3RN8 was -6.61 kcal mol^-1, while the binding energy of Allin was -8.08 kcal mol^-1. Furthermore Alliin's affinity to the other AMPA and NMDA receptors is quite satisfactory compared to the reference molecule glutamate. In conclusion based on the molecular docking study, Alliin can be useful for synaptic plasticity studies whereas might be enhance seizure activity because of the increased permeability to cations. It also can be beneficial to improve learning and memory and can be used as a supportive product to the hypofunction of NMDA associated problems.

Ortho versus Meta Chlorophenyl-2,3-Benzodiazepine Analogues: Synthesis, Molecular Modeling, and Biological Activity as AMPAR Antagonists

2,3-Benzodiazepine compounds are an important family of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) antagonists that act in a noncompetitive manner. Due to the critical role of AMPARs in the synapse and various neurological diseases, significant scientific interest in elucidating the molecular basis of the function of the receptors has spiked. The analogues were synthesized to assess the functional consequence of removing the amine group of the phenyl ring, the potency and efficacy of inhibition by substituting a halogen group at the meta vs ortho position of the phenyl ring, and layout the prediction of potential drug candidates for AMPAR hyperactivation. Using the whole-cell patch-clamp technique, we assessed the effect of the derivative on the amplitude of various AMPA-type glutamate receptors and calculated the desensitization and deactivation rates before and after treatment of HEK293 cells. We noticed that the amino group is not necessary for inhibition as long as an electron-withdrawing group is placed on the meta position of the phenyl ring of BDZ. Furthermore, compound 4a significantly inhibited and affected the desensitization rate of the tested AMPARs but showed no effect on the deactivation rate. The current study paves the way to a better understanding of AMPARs and provides possible drug candidates of 2,3-BDZ different from the conventional derivatives.

AMPA Receptor Noncompetitive Inhibitors Occupy a Promiscuous Binding Site

Noncompetitive inhibitors of AMPA receptors have attracted interest in recent years as antiepileptic drugs. However, their development is hindered by a lack of detailed understanding of the protein-inhibitor interaction mechanisms. Recently, structures of AMPA receptor complexes with the structurally dissimilar, noncompetitive, small-molecule inhibitors pyridone perampanel (PMP), GYKI 53655 (GYKI), and CP 465022 (CP) were resolved, revealing that all three share a common binding site. However, due to the low resolution of the ligands, their exact binding modes and protein-ligand interactions remain ambiguous and insufficiently detailed. We carried out molecular dynamics (MD) simulations on X-ray-resolved and docked AMPA receptor complexes, including thermodynamic integration (TI) to compute ligand binding constants, in order to investigate the inhibitor binding modes in detail and identify key protein-ligand interaction mechanisms. Our analysis and simulations show that the ligand binding pocket at the interface of the receptor's transmembrane domain exhibits features also found in the binding pockets of the multidrug-resistance proteins. The inhibitors bind to such promiscuous pockets by forming multiple weak contacts, while the large, flexible pocket undergoes adjustments to accommodate structurally different ligands in different orientations. TI was able to identify a specific more favorable binding mode for GYKI, while PMP, which has a symmetric ring structure, produced several comparable poses indicating that it may bind in several orientations.

Chirality as an Important Factor for the Development of New Antiepileptic Drugs

In recent years, chiral molecules (especially enantiomers) have occupied a significant place in pharmaceutical industry and have played a prominent role in the development of new drugs. Individual stereoisomers exhibit marked differences in pharmacodynamic, pharmacokinetic, and toxicological properties. Therefore, there is currently considerable interest in fully characterizing and examining both enantiomers in the early stages of new drug development. Despite the fact that epilepsy is a complex disease and that a given drug's mechanism of action may be multidirectional and not always fully understood, significant differences have been observed in the anticonvulsant activity of individual stereoisomers. Therefore, between 1996 and 2018, among 14 new antiepileptic drugs (AEDs) approved for the treatment of epilepsy, as many as seven are chiral and introduced to the market in the single-enantiomer (or diastereomer) form. This review provides an overview of the impact of chirality on the development and discovery of new AEDs that have entered into clinical trials or preclinical studies. These new AEDs were developed by applying the single-enantiomer approval strategy. Herein we focus our attention on the main synthetic pathways of stereoisomers, as well as on the influence of chirality on pharmacodynamic, pharmacokinetic, and/or toxicological properties.

Facile synthesis of 2,3-benzodiazepines using one-pot two-step phosphate-assisted acylation–hydrazine cyclization reactions

We present a one-pot two-step methodology, in which an unprotected amino is tolerated, for rapidly synthesizing 2,3-benzodiazepines via phosphate-assisted acylation reaction and hydrazine cyclization reaction.

Structural Bases of Noncompetitive Inhibition of AMPA-Subtype Ionotropic Glutamate Receptors by Antiepileptic Drugs

Excitatory neurotransmission plays a key role in epileptogenesis. Correspondingly, AMPA-subtype ionotropic glutamate receptors, which mediate the majority of excitatory neurotransmission and contribute to seizure generation and spread, have emerged as promising targets for epilepsy therapy. The most potent and well-tolerated AMPA receptor inhibitors act via a noncompetitive mechanism, but many of them produce adverse side effects. The design of better drugs is hampered by the lack of a structural understanding of noncompetitive inhibition. Here, we report crystal structures of the rat AMPA-subtype GluA2 receptor in complex with three noncompetitive inhibitors. The inhibitors bind to a novel binding site, completely conserved between rat and human, at the interface between the ion channel and linkers connecting it to the ligand-binding domains. We propose that the inhibitors stabilize the AMPA receptor closed state by acting as wedges between the transmembrane segments, thereby preventing gating rearrangements that are necessary for ion channel opening.